Most types of headgear worn by workers to protect the worker's head from falling objects are held on the worker's head by a suspension system. The suspension system, along with the helmet itself, act to absorb the shock of a falling object striking the worker's head.
The suspension is a web-like support system comprised of two or more strips of material that are arranged to cross each other. The ends of the strips are attached at four or more points around the circumferential interior of the hat or helmet. A headband is then attached to the four or more points of the suspension to permit the helmet to be worn by the worker. A napestrap is attached to one end of the headband. In order to securely position the helmet on the worker's head, it is essential that the circumferences of the suspension be adjustable to fit the appropriate head size.
Two types of helmet suspensions that are now known in the art are the Fas-Trac.TM. Ratchet Suspension and the Staz-on.TM. Suspension, both manufactured and sold by Mine Safety Appliances Company of Pittsburgh, Pa. The Staz-on Suspension features an adjustable napestrap that is manually adjusted by the wearer. The two ends of the napestrap are connected and held in place by a slot and teeth arrangement. One end of the napestrap is formed with parallel rows of teeth. The other end of the napestrap is formed with parallel rows of slots. The size of the suspension can then be adjusted by inserting the teeth of one end of the strap into the slots formed in the other end of the strap t the desired length.
The second type of suspension has an adjustable napestrap where the ends of the strap are connected, held in place and adjusted by a ratchet mechanism. The ratchet mechanism operates on a gear and teeth arrangement. The ratchet adjustment knob has attached to it at one end a set of cog teeth. These teeth are then positioned inside of a lateral section of the napestrap. The section of the napestrap has rows of slots formed along the inside of the strap. By placing the adjustment knob in contact with the slot, the size of the napestrap can be adjusted by turning the knob one direction to pull the strap ends closer together or turning the knob the other direction to force the ends apart. A metal spring placed near the adjustment knob locks one of the adjustment knob teeth against a pin attached to the inside of the casing to prevent adjustment knob from turning and the straps ends from pulling apart.
The ratchet suspension is preferred over the adjustable napestrap suspension because the suspension can be easily adjusted while on the head of the worker. There are, however, certain disadvantages to the ratchet type suspension. The ratchet suspension has numerous component parts that must be assembled to operate the ratchet. The number of parts and the labor required to assemble the parts is quite costly. The ratchet suspensions are often so costly that many workers purchase the simple adjustable napestrap even though the adjustable napestrap does not offer the ease of operation or stability of the suspension of that offered by the ratchet. Another disadvantage of the ratchet suspension is the need for the metal spring used to fix the ends of the napestrap together. The metal spring can place an electrical conductor in the hat suspension that can render the suspension unusable for work around electricity or electric wires. Additionally, metal screws are also used to attach the adjustment knob and spring.
The object of this invention is to provide a suspension system that possesses the maneuverability and adjustability of the ratchet system yet is inexpensive to make, easy to assemble and eliminates the metal spring by providing a unique pre-molded spring mechanism in the gear adjustment knob, as well as all other metal parts.